A method for the preparation of a 2-hydroxyarylaldehyde which comprises reacting an aryloxymagnesium halide derived from a phenol having at least one free ortho position relative to the phenolic hydroxy group with formaldehyde or a formaldehyde-liberating compound under substantially anhydrous conditions in the presence of a polar organic solvent other than hexamethylphosphoramide or 1,3-dimethyl-3,4,5,6-2(1H)-pyrimidone.